Reduced thoracolumbar fascia shear strain in human chronic low back pain

PainSci » bibliography » Langevin et al 2011
updated Oct 4, 2017

Tags: etiology, back pain, fascia, anatomy, neat, pro, pain problems, spine, controversy, debunkery, massage, manual therapy, treatment

Three pages on PainSci cite Langevin 2011: 1. Massage Therapy for Low Back Pain (Again) 2. The Complete Guide to Low Back Pain 3. Does Fascia Matter?

PainSci notes on Langevin 2011:

This is an ultrasound study of the motion of layers of connective tissue in the low back in 70 people with chronic low back pain compared to 50 healthy people. It’s a follow-up to a closely related 2009 study (Langevin) which showed that the thoracolumbar fascia is about 25% thicker in people with low back pain. Subjects lay on a motorized table that flexed their lower backs, while a probe inserted under their skin took an ultrasound “movie” of their thoracolumbar fascia. The images showed that it stretched about 20% less in patients with back pain. (Specifically, the “shear strain” was about 20% less. Shear strain is a measurement of the deformation of a structure.)

So according to the pair of papers, people with chronic back pain have somewhat thick, stiff connective tissues in the area. The clinical significance of this is unknown and beyond the scope of their experiments: we don’t know what it’s telling us. Willard et al write:

The reduction in shear-strain could be due to tissue adhesions induced by previous injury or inflammation, and could then be consistent with the proposed etiology suggested by Dittrich (1963) and Bednar et al. (1995). However, as the authors of this recent study emphasize themselves, it is also possible that the observed tissue changes are merely the result of a reduction (immobility) in everyday lumbar movements related to low back pain. In this case, the fascial changes would be the effect of low back pain rather than a cause.

Even simpler — and simpler explanations are always well worth considering — the effect may not even be a case of “tissue changes,” but simply that tension on the thoracolumbar fascia is higher as a dynamic response to pain in the region. It is being “held tighter” in other words, and adapting over time by getting thicker.

Back pain is an extremely complex phenomenon. These findings are interesting, but may not be consistently measurable, and there has been no independent replication. It’s par for the course for findings like this to be elusive. As ever in science and life, what you “see” depends on how you “look.” And, sure enough, in 2016 the same research group claim to have reproduced the same results in pigs by injuring them (Bishop), and then again in 2017 with the additional aim of testing the effect of stretching (Langevin). Until there’s independent replication, however, I am not taking their word for anything.

original abstract †Abstracts here may not perfectly match originals, for a variety of technical and practical reasons. Some abstacts are truncated for my purposes here, if they are particularly long-winded and unhelpful. I occasionally add clarifying notes. And I make some minor corrections.

BACKGROUND: The role played by the thoracolumbar fascia in chronic low back pain (LBP) is poorly understood. The thoracolumbar fascia is composed of dense connective tissue layers separated by layers of loose connective tissue that normally allow the dense layers to glide past one another during trunk motion. The goal of this study was to quantify shear plane motion within the thoracolumbar fascia using ultrasound elasticity imaging in human subjects with and without chronic low back pain (LBP).

METHODS: We tested 121 human subjects, 50 without LBP and 71 with LBP of greater than 12 months duration. In each subject, an ultrasound cine-recording was acquired on the right and left sides of the back during passive trunk flexion using a motorized articulated table with the hinge point of the table at L4-5 and the ultrasound probe located longitudinally 2 cm lateral to the midline at the level of the L2-3 interspace. Tissue displacement within the thoracolumbar fascia was calculated using cross correlation techniques and shear strain was derived from this displacement data. Additional measures included standard range of motion and physical performance evaluations as well as ultrasound measurement of perimuscular connective tissue thickness and echogenicity.

RESULTS: Thoracolumbar fascia shear strain was reduced in the LBP group compared with the No-LBP group (56.4% ± 3.1% vs. 70.2% ± 3.6% respectively, p < .01). There was no evidence that this difference was sex-specific (group by sex interaction p = .09), although overall, males had significantly lower shear strain than females (p = .02). Significant correlations were found in male subjects between thoracolumbar fascia shear strain and the following variables: perimuscular connective tissue thickness (r = -0.45, p <.001), echogenicity (r = -0.28, p < .05), trunk flexion range of motion (r = 0.36, p < .01), trunk extension range of motion (r = 0.41, p < .01), repeated forward bend task duration (r = -0.54, p < .0001) and repeated sit-to-stand task duration (r = -0.45, p < .001).

CONCLUSION: Thoracolumbar fascia shear strain was ~20% lower in human subjects with chronic low back pain. This reduction of shear plane motion may be due to abnormal trunk movement patterns and/or intrinsic connective tissue pathology. There appears to be some sex-related differences in thoracolumbar fascia shear strain that may also play a role in altered connective tissue function.

original abstract †Abstracts here may not perfectly match originals, for a variety of technical and practical reasons. Some abstacts are truncated for my purposes here, if they are particularly long-winded and unhelpful. I occasionally add clarifying notes. And I make some minor corrections.

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